Re: [lwip-devel] Single TCP socket to handle IPv4 and IPv6 traffic

[Rahul Gundecha]

Thanks Simon and Sylvain for the response.

I am not using IPv4-mapped IPv6 address.

I have a IPv4 socket running on port 80. I anticipated that HTTP request from IPv4 hosts will reach this socket, whereas requests from IPv6 hosts should not. However it is not the case. I can see packets from IPv6 hosts also received on the same socket. Entire TCP request-response workflow works well using the device's IPv6 address if the initial TCP request is from IPv6 host.

However if there is TCP SYN flood from IPv6 hosts, then the TCP listen backlog queue gets full. Hence the fix mentioned in the earlier patch is required. I knew that this fix is not the right fix. However the rest of the lwip stack processes IPv6 requests seamlessly even if socket is configured for IPv4. So question is here whether this handling is purposefully kept simple or its work to be done? In later case my fix is not required.

On the other hand, I always have first option to accomplish this requirement:
> >1) Have 2 sockets, one for IPv4, other for IPv6.

Thanks,

Rahul

On Fri, Mar 27, 2015 at 2:01 AM, address@hidden <address@hidden> wrote:

Sylvain Rochet wrote:

I guess he is talking about IPv4-mapped IPv6 addresses, it works very
well in Linux and is actually the default.

I don't think he is:
> However I observed that the existing socket which is configured for IPv4 is also able to accept
> and process IPv6 traffic, without any extra configuration.

As this sentence seems wrong, I asked him what he was doing. The proposed fix is wrong, anyway.

Keeping that aside, dual-version handling of course has to be implemented in lwIP.

Simon

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